Hymenolaimus malacorhynchos (blue duck, whio)

Hymenolaimus malacorhynchos, the blue duck or whio is the only member of the genus Hymenolaimus. It is a slate-blue colour and has a characteristically pale bill.

It is one of only 3 species amongst the world’s 159 waterfowl that live all year round on fast-flowing rivers. The others are found in South America (the torrent duck) and New Guinea (Salvadori’s duck).

This duck’s presence indicates a healthy river - it acts as a key indicator species of river quality.

Hymenolaimus malacorhynchos is endemic to New Zealand where the Maori name whio (pronounced fee-o) describes the high-pitched, wheezy whistle call that is made by the male.

About the author

A word from the author

"The blue duck is a truly unique species. Its physical adaptations and habits are like no other duck. Endemic to New Zealand and only found on mountain rivers, its numbers are declining. Its presence indicates a ‘healthy’ river and they are therefore a key indicator species of river quality. For these reasons alone every effort should be made to secure the future of this remarkable and charismatic species."